Peptide fragment corresponding to residues 1 - 40 of Nogo-66, the domain of the myelin protein Nogo that inhibits axonal outgrowth. Acts as a competitive antagonist at the Nogo-66 receptor (NgR); blocks Nogo-66- and CNS myelin-induced inhibition of axonal growth, but does not reduce myelin-associated glycoprotein (MAG) inhibition of neurite outgrowth in vitro. Promotes regeneration of hemisected spinal axons and locomotor recovery following spinal injury in vivo. MW (observed): 4625.16.